1. Field of the Invention
The present invention relates to a memory device and a method of manufacturing the same, and more particularly, to a memory device including a dielectric thin film having a plurality of dielectric layers and a method of manufacturing the same.
2. Discussion of Related Art
Non-volatile memory devices are information storage devices typically employed in cellular phones, digital cameras, MP3 players, and the like. The use of non-volatile memory devices in these and various other devices is extremely widespread, and demand for mass storage of data is recently increasing. In addition, non-volatile memory devices are commonly used in mobile devices which require that they operate at low power.
Flash memory devices, which control accumulation of charge on a floating gate to store data, are the most widespread type of non-volatile memory device. However, since flash memory devices have a structure in which charge is accumulated on a floating gate in the presence of a strong electric field, the device structure becomes relatively complicated and difficult to densely integrate.
To overcome this problem, the Ovonic Unified Memory (OUM), an electrically erasable non-volatile memory device, was proposed. The OUM uses a difference in electrical conductivity between a crystalline state and a non-crystalline state of a memory layer, and has a simple structure compared to a flash memory so that it can be highly integrated in theory. However, heat is required for a phase change from the crystalline state to the noncrystalline state of the memory layer in the OUM, which requires a current of about 1 mA per cell. Consequently, thick interconnections are required, which again makes it difficult to obtain high integration.
To cope with this problem, non-volatile memory devices allowing an electrical resistance to change without a phase change are disclosed in Korean Patent Publication No. 2004-0049290 and Japanese Laid-Open Patent Publication No. 2004-185756. The non-volatile memory devices disclosed in these documents are based on the principle of forming an oxide having a perovskite structure containing Mn and applying a voltage pulse to change electrical resistance.
However, materials such as Mn oxide layers disclosed in the cited documents (e.g., PrCaMnO, LaCaMnO, LaCaPbMnO, or the like) require a high process temperature and have complicated structures. Consequently, manufactured strictures may easily deviate from what is necessary for the memory device to function properly. Accordingly, such devices are difficult to manufacture.